The present invention relates generally to mounting systems for rotary dampers used on motorcycles.
More particularly, this invention pertains to mounting system for a rotary damper that reduces the amount of undamped motion associated with typical prior art mounting systems, while at the same time preventing any binding or interference with smooth steering action that results when these prior art systems are modified in an attempt to reduce this undamped motion.
Under certain conditions, the steering system in a motorcycle can become unstable and develop rapidly increasing rotational oscillations in the steering head of the steering system. This condition is commonly referred to as “head shake” and results, in part, because the steering geometry of a motorcycle, and particularly a racing motorcycle, is designed so that there is a compromise between front end stability and easy and quick steering.
During normal operating conditions, a motorcycle steering system may be stable and safe. However, if the steering system is disturbed by bumps, reduced loads during acceleration, or the front wheel contacting the ground after it has been raised in the air during very quick acceleration, head shake may occur.
Head shake is not a new phenomenon and is typically addressed using a steering damper, which reduces head shake and maintains a motorcycle in a safe operation condition. One particular type of steering damper that is known in the art is a rotary damper that mounts coaxially with the steering pivot axis of a motorcycle. More specifically, this type of damper generally mounts to the top surface of a top triple clamp included as part of the motorcycle steering system and includes a damped member that acts on the frame of the motorcycle to provide the resistance forces necessary for the damping effect. An example of a prior art rotary damper is described in U.S. Pat. No. 6,899,208, which was issued to the applicant for the present invention and is hereby incorporated by reference in its entirety.
Mounting systems for rotary dampers are also known in the art. These systems are typically designed to allow for misalignment in the damper, the damped member, and the motorcycle frame interface. The more common designs for these systems employ a slot in the damped member that interfaces with a peg or post mounted to the frame of a motorcycle. This type of design, however, has several disadvantages. For example, this type of design requires clearances, or free play, at the interface of the members that must be large enough to allow for rotational misalignment, as well as small amounts of linear motion as the steering head is rotated. This is true because the damper axis is usually mounted non-concentric with the steering axis of the motorcycle. These clearances cause a certain amount of undamped motion to occur during operation of a motorcycle, which is undesirable. While the clearances can be reduced in order to reduce this undamped motion, this causes the mounting system to bind and interfere with smooth steering action—another equally undesirable result.
Another disadvantage of existing prior art mounting systems is that these systems are mounted over other motorcycle steering elements and must be completely removed before maintenance can be performed on these elements.
What is needed, then, is a mounting system for a rotary damper on a motorcycle that eliminates the disadvantages associated with existing prior art mounting systems for these dampers.